I'm afraid electrical circuits don't work quite like that, although it must be said that it's indeed a valiant attempt at rationality. Typically, you see, anything that causes a source and a load to transition away from a matched state will result in less power being transferred from source to load, not more.

So an easy way to test if the EMdrive works, would be to build a low power unit (1 watt or less). Then with the system powered and tuned move it! Any movement along the thrust axis should have a corresponding effect on the cavity resonance. This may be far easier to detect and confirm than the very small forces developed so far.

Mike

Good idea! Thanks.

Don't need to power it as such. Just use a spectrum analyser to detect resonant frequency changes with acceleration.

Have added that to my list of things to test.

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"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”Herman Melville, Moby Dick

I'm afraid electrical circuits don't work quite like that, although it must be said that it's indeed a valiant attempt at rationality. Typically, you see, anything that causes a source and a load to transition away from a matched state will result in less power being transferred from source to load, not more.

So an easy way to test if the EMdrive works, would be to build a low power unit (1 watt or less). Then with the system powered and tuned move it! Any movement along the thrust axis should have a corresponding effect on the cavity resonance. This may be far easier to detect and confirm than the very small forces developed so far.

Mike

Earth is rotating and orbiting the sun, and there's all sorts of electronic devices where nothing was ever observed to vary with the time of day, down to very high precision.

Frustum would need to constantly accelerate to be able to see resonant frequency changes.

« Last Edit: 05/19/2015 02:43 PM by TheTraveller »

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"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”Herman Melville, Moby Dick

Ultimately what Shawyer's and White's theories amount to, is that there is a radiation pressure imbalance on the inside of the cavity, resulting in a net force, which is a non small fraction of the total radiation pressure on the inside of the cavity (more than 1%). Shawyer says it is in accordance with Maxwell's equations, which is flat out wrong.

Where is Shawyer wrong?

1) Is the cutoff wavelength different at the small and big ends or not?

2) Is the guide wavelength different at the small and big ends or not?

3) Is the group velocity different at the small and big ends or not?

4) Is the bounce force different at the small and big ends or not?

5) Is the bounce force at the big end greater than at the small end or not?

6) Is there a bounce force on the side walls or not?

Just trying to understand where you believe Shawyer is wrong?

Well, firstly, Shawyer has greater radiation pressure upon the wide end, but his drive is pushing narrow end forwards.

Secondarily, yes, there is an interaction between the EM field and the walls, which results in a force on the side walls, equal to change in momentum of the EM field travelling down it, per time.

Ultimately what Shawyer's and White's theories amount to, is that there is a radiation pressure imbalance on the inside of the cavity, resulting in a net force, which is a non small fraction of the total radiation pressure on the inside of the cavity (more than 1%). Shawyer says it is in accordance with Maxwell's equations, which is flat out wrong.

Where is Shawyer wrong?

1) Is the cutoff wavelength different at the small and big ends or not?

2) Is the guide wavelength different at the small and big ends or not?

3) Is the group velocity different at the small and big ends or not?

4) Is the bounce force different at the small and big ends or not?

5) Is the bounce force at the big end greater than at the small end or not?

6) Is there a bounce force on the side walls or not?

Just trying to understand where you believe Shawyer is wrong?

Well, firstly, Shawyer has greater radiation pressure upon the wide end, but his drive is pushing narrow end forwards.

Secondarily, yes, there is an interaction between the EM field and the walls, which results in a force on the side walls, equal to change in momentum of the EM field travelling down it, per time.

Maxwell has a cosine factor to adjust for waves that hit the bounce surface at an angle. Max force at the end plates and min force at the walls as attached.

CofM requires if the EM waves pushes more on the on the big end than the small end, the EM Drive frustum pushes back in the opposite direction of the imbalance. Momentum transfer is not one sided. If the EM Drive moved toward the big end, then CofE would be violated as only a one sided push.

That effect is very clear and confirmed in the Demonstrator rotary tests:http://emdrive.com/dynamictests.htmlwhere you can see the movement direction and that the unit is continually accelerating / speeding up over time.

The number of photons (N) inside a cavity is not conserved. A photon may collide with an electron on a wall, exciting it to a higher energy state, removing a photon. This electron may drop back to its lower level in a series of steps, each one of which releases an individual photon back into the cavity. Although the sum of the energies of the emitted photons are the same as the absorbed photon, the number of emitted photons will vary.

The absorption (emission) of one photon might be accompanied by the emission (absorption) of more than one photon, as long as the frequency of the photons involved are such that the energy of the system remains constant.

N over volume, and the entropy density are proportional to the cube of the temperature of the photon gas, while the pressure and the energy density are proportional to the fourth power of its temperature.

For black body radiation it can be shown that, as a result of this lack of constraint on the number of photons in the system, the chemical potential of the photons must be zero.

One point to keep in mind is that the change from 2GHz to ambient thermal radiation is an up-conversion, that is, it represents a negative entropy change component that must be more than made up somewhere else.

Ah, found it. Dr. Rodal please note well the highlighted section in the 2nd attachment.

Here is how Shawyer measured his 2 force measurements on his Demonstrator EM Drive as per the 4th results line of the 1st attachment.

He used the rotary test rig and measured the acceleration and deceleration forces generated by the EM Drive. Did this in both directions. IE CW acceleration, then CW deceleration, then CCW acceleration, then CCW deceleration.

Ah, found it. Dr. Rodal please note well the highlighted section in the 2nd attachment.

Here is how Shawyer measured his 2 force measurements on his Demonstrator EM Drive as per the 4th results line of the 1st attachment.

He used the rotary test rig and measured the acceleration and deceleration forces generated by the EM Drive. Did this in both directions. IE CW acceleration, then CW deceleration, then CCW acceleration, then CCW deceleration.

Clever boy our Roger.

Thank you for the information.

My question was how were the two forces (what Shawyer calls "reaction" and "thrust") measured simultaneously (I had labored to use Italics first and then bold and blue to highlight "simultaneously").

From the description provided it looks like there has been no experiment measuring simultaneously the two forces (what Shawyer calls "reaction" and "thrust") that Shawyer claims to exist.

The "thrust" force is an explanation by Shawyer to explain conservation of momentum, to explain that Newton's third law of action and reaction is being obeyed. There is no experimental measurement of this "thrust" force simultaneously performed to verify its existence.

All that is being measured is displacement vs. time (or its second-order derivative with respect to time, whatever its sign) of the device

The problem with making measurements of acceleration (positive and negative) and then ascribing the results to the two forces are evident.

My question was how were the two forces (what Shawyer calls "reaction" and "thrust") measured simultaneously (I had labored to use Italics first and then bold and blue to highlight "simultaneously").

From the description provided it looks like there has been no experiment measuring simultaneously the two forces (what Shawyer calls "reaction" and "thrust") that (quoting you) "Clever boy our Roger" claims to have measured.

All that is being measured is displacement vs. time (or its second-order derivative with respect to time, whatever its sign) of the device

The problem with making measurements in acceleration and deceleration and then ascribing the results to the two forces are evident.

What Shawyer displayed are the forces measured on the Em Drive Demonstrator Engine as it accelerated for some time (gaining velocity / kinetic energy) and then decelerated (losing velocity / kinetic energy) for some time as the unit rotated in the same direction on the rotary turntable. Then the process was repeated with the EM Drive rotating in the opposite direction. Is what Shawyer calls Motor & Generator mode.

Never read where Shawyer claimed to have measured them at the same time. Can you please point out where he claimed to have done that? If not why mention it being done simultaneously?

Anyway we now know how the 2 measurements were done and what they mean.

BTW in Generator mode, the reducing craft kinetic energy is turned into additional cavity energy. As you can't turn increased frustum microwave energy back into electrical energy, it will heat up the frustum, acting as does a car's break, converting unwanted kinetic energy into heat energy.

What the 2 measurements show are the ability of the Demonstrator Engine to either be a kinetic energy source during acceleration (motor mode) or a kinetic energy sink during deceleration (generator mode).

And yes, in my opinion, it is a clever test to show/prove Motor/Generator operation is real.

The bread crumb trail is there, just need to find them and follow them to where the bread crumbs / data leads you.

« Last Edit: 05/19/2015 04:51 PM by TheTraveller »

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"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”Herman Melville, Moby Dick

...there is an interaction between the EM field and the walls, which results in a force on the side walls, equal to change in momentum of the EM field travelling down it, per time.

I was thinking there should be forces on the side walls also. I did an experiment once with an aluminum ring and a changing magnetic field and observed forces on it once that seemed to make it more obvious for me what should be going on in the side walls. I don't think it explains why the drive would accelerate as I think Maxwell's equations would just give that the forces balance out for a static solution. My guess is something asymmetric is going on in the drive with time and I suspect it to be a diametric drive where currents interacting with radiation are giving an effective negative mass for one side of the drive and an effective positive mass for currents interacting with the other side.

Sort of like if you drive the current in the aluminum ring the opposite direction that the radiation would drive it then it attracted instead of repelled. Then extend that to two aluminum rings and play with the phase in space and time.

Hello. I've been reading this thread and Iulian's blog with great interest. I'm just wondering if all of the calculations on possible thrust have only been done on truncated cones or cylinders... after Mr. Iulian retries his experiment inverting the frustrum to see if it's a metal hot air balloon, I'm curious what would happen if...one used a conical bore similar to the bell of a brass musical instrument. As an experiment, has anyone tried these experiments using a shape similar to the bell end of a tuba, sousaphone, french horn, etc? It would probably be pretty easy to try this experiment using a shape similar to this... maybe with a different material? If this has been addressed (or if a dumb question) I'll remove my post...thanks!

I was wondering if we would be able to get a faster turnaround with prototyping and maybe even cut costs if we could use 3D printing and e.g. conductive graphene filament like this one:

We could share computer designs and use local 3D printing services. Would that work?

That's what I've been planning on doing. Makes construction a great deal simpler for some of the pieces. I'm getting the bottom plate printed in aluminum and I will drill and tap the bolt holes myself. This makes it much easier to create the spherical concave surface.

Rated at 100 mA for 12 V it seems limited to non current carrying use with power levels under discussion. Website mentions EMI shielding as a potential application. High strength when compared with PLA and ABS could be a useful property in this case.

Will have to think about how to compare this material with sheet copper or aluminum used in fabricating the cavities, might be helpful in making a set of rings as depicted in Rodals attachment upthread;NASA, Shawyer, Yang, and other EM Drive researchers would be well advised to experiment with replacing the end plates of the EM Drive with this system of concentric rings, in order to address the problem of air convection currents that has plagued radiation pressure experiments in ambient conditions ever since Maxwell 140 years ago. Even in a partial vacuum, if one uses for example bilayer plates of copper/glass-fiber-reinforced epoxy with the reinforced polymer on the external surface, there is the possibility of outgassing in a vacuum producing a false positive. The use of a mesh precludes this problem both in ambient air conditions and in a vacuum.

I'm afraid electrical circuits don't work quite like that, although it must be said that it's indeed a valiant attempt at rationality. Typically, you see, anything that causes a source and a load to transition away from a matched state will result in less power being transferred from source to load, not more.

So an easy way to test if the EMdrive works, would be to build a low power unit (1 watt or less). Then with the system powered and tuned move it! Any movement along the thrust axis should have a corresponding effect on the cavity resonance. This may be far easier to detect and confirm than the very small forces developed so far.

Mike

Earth is rotating and orbiting the sun, and there's all sorts of electronic devices where nothing was ever observed to vary with the time of day, down to very high precision.

Frustum would need to constantly accelerate to be able to see resonant frequency changes.

We could pull it behind my 65 Pontiac Catalina. NASA has already proven that a 421 powered Pontiac will make things fly.

Hello. I've been reading this thread and Iulian's blog with great interest. I'm just wondering if all of the calculations on possible thrust have only been done on truncated cones or cylinders... after Mr. Iulian retries his experiment inverting the frustrum to see if it's a metal hot air balloon, I'm curious what would happen if...one used a conical bore similar to the bell of a brass musical instrument. As an experiment, has anyone tried these experiments using a shape similar to the bell end of a tuba, sousaphone, french horn, etc? It would probably be pretty easy to try this experiment using a shape similar to this... maybe with a different material? If this has been addressed (or if a dumb question) I'll remove my post...thanks!

Welcome to the thread . Other shapes have been tried, for example, the Cannae drive:

Please note that instead of air molecules vibrating as sound waves inside a musical instrument in the 10^3 Hz range, the EM Drive has photons oscillating as electromagnetic waves in the 10^9 Hz microwave frequency, hence the mode shapes are quite different than for musical instruments.

Ultimately what Shawyer's and White's theories amount to, is that there is a radiation pressure imbalance on the inside of the cavity, resulting in a net force, which is a non small fraction of the total radiation pressure on the inside of the cavity (more than 1%). Shawyer says it is in accordance with Maxwell's equations, which is flat out wrong.

Where is Shawyer wrong?

1) Is the cutoff wavelength different at the small and big ends or not?

2) Is the guide wavelength different at the small and big ends or not?

3) Is the group velocity different at the small and big ends or not?

4) Is the bounce force different at the small and big ends or not?

5) Is the bounce force at the big end greater than at the small end or not?

6) Is there a bounce force on the side walls or not?

Just trying to understand where you believe Shawyer is wrong?

1-2-3) It really doesn't make sense to talk about "group velocity", "cutoff wavelength" for different "ends" in this case. A cavity is not a waveguide. Introducing end plates (whether curved or flat) changes the boundary conditions and thus the mode structure of the EM fields. There is just one cutoff wavelength for the entire cavity, much like an organ pipe has one "fundamental" tone.

Please understand that Egan's calculation of the fields is an exact solution of Maxwell's equations. Shawyer's talk about waveguides is at best a sloppy approximation.

4-5-6) There are forces on all surfaces of the cavity. Again referring to Egan's website, in the standard formulation of Maxwell's equations, for any closed cavity supporting time-harmonic fields, the integral of forces on the walls vanishes. To suggest Maxwell's equations say otherwise is just bad physics.

Generically, a question I asked many many pages ago, and that everyone has danced around: if the EM drive works, we must have a non-classical coupling of electromagnetic fields to something else. Why has this coupling never been observed before? What is special about a copper cone?

Incidentally, here is my (modest) proposal for an experiment to prove or disprove if there is anything going on here:

1. Place a well-insulated (or otherwise thermally massive) EM drive on a linkage that causes it to move back and forth such that the cavity experiences sinusoidally varying acceleration.2. Monitor the resonant frequency (with a VNA or spectrum analyzer).3. See if there are any changes in center frequency with the same period as the acceleration.

Care should be taken to ensure that strain in cables or connectors does not induce spurious shifts in resonant frequencies, but by basically doing a form of lock-in measurement you can massively reduce any source of noise or interference.

This would be thousands of times more accurate than trying to measure minuscule forces and trying to rule out the classical explanations for them.

Ultimately what Shawyer's and White's theories amount to, is that there is a radiation pressure imbalance on the inside of the cavity, resulting in a net force, which is a non small fraction of the total radiation pressure on the inside of the cavity (more than 1%). Shawyer says it is in accordance with Maxwell's equations, which is flat out wrong.

Where is Shawyer wrong?

1) Is the cutoff wavelength different at the small and big ends or not?

2) Is the guide wavelength different at the small and big ends or not?

3) Is the group velocity different at the small and big ends or not?

4) Is the bounce force different at the small and big ends or not?

5) Is the bounce force at the big end greater than at the small end or not?

6) Is there a bounce force on the side walls or not?

Just trying to understand where you believe Shawyer is wrong?

1-2-3) It really doesn't make sense to talk about "group velocity", "cutoff wavelength" for different "ends" in this case. A cavity is not a waveguide. Introducing end plates (whether curved or flat) changes the boundary conditions and thus the mode structure of the EM fields. There is just one cutoff wavelength for the entire cavity, much like an organ pipe has one "fundamental" tone.

Please understand that Egan's calculation of the fields is an exact solution of Maxwell's equations. Shawyer's talk about waveguides is at best a sloppy approximation.

4-5-6) There are forces on all surfaces of the cavity. Again referring to Egan's website, in the standard formulation of Maxwell's equations, for any closed cavity supporting time-harmonic fields, the integral of forces on the walls vanishes. To suggest Maxwell's equations say otherwise is just bad physics.

Generically, a question I asked many many pages ago, and that everyone has danced around: if the EM drive works, we must have a non-classical coupling of electromagnetic fields to something else. Why has this coupling never been observed before? What is special about a copper cone?

To clarify your point, electromagnetic fields can be measured directly, without measuring tiny forces. A page back I posted a rough calculation: to get >50uN from 50W pumped into a cavity with a Q of ~7000 , the microwaves at the surface of the cavity must deviate from the accepted solution by at least ~2.5% . (With Cannae drive giving similar results, the cavity shape is clearly not very important).

Needless to say we did successfully detect - electrically - effects trillions times weaker than that.

Ultimately what Shawyer's and White's theories amount to, is that there is a radiation pressure imbalance on the inside of the cavity, resulting in a net force, which is a non small fraction of the total radiation pressure on the inside of the cavity (more than 1%). Shawyer says it is in accordance with Maxwell's equations, which is flat out wrong.

Where is Shawyer wrong?

1) Is the cutoff wavelength different at the small and big ends or not?

2) Is the guide wavelength different at the small and big ends or not?

3) Is the group velocity different at the small and big ends or not?

4) Is the bounce force different at the small and big ends or not?

5) Is the bounce force at the big end greater than at the small end or not?

6) Is there a bounce force on the side walls or not?

Just trying to understand where you believe Shawyer is wrong?

1-2-3) It really doesn't make sense to talk about "group velocity", "cutoff wavelength" for different "ends" in this case. A cavity is not a waveguide. Introducing end plates (whether curved or flat) changes the boundary conditions and thus the mode structure of the EM fields. There is just one cutoff wavelength for the entire cavity, much like an organ pipe has one "fundamental" tone.

Please understand that Egan's calculation of the fields is an exact solution of Maxwell's equations. Shawyer's talk about waveguides is at best a sloppy approximation.

4-5-6) There are forces on all surfaces of the cavity. Again referring to Egan's website, in the standard formulation of Maxwell's equations, for any closed cavity supporting time-harmonic fields, the integral of forces on the walls vanishes. To suggest Maxwell's equations say otherwise is just bad physics.

Generically, a question I asked many many pages ago, and that everyone has danced around: if the EM drive works, we must have a non-classical coupling of electromagnetic fields to something else. Why has this coupling never been observed before? What is special about a copper cone?

Both Shawyer & the Chinese claim their many physical devices produce thrust and the measurement of that thrust is in agreement with their theoretical calculations.

Both claim no new physics is needed and CofE / CofM are conserved.

Both use a different approach to calculate the thrust, yet come up with the same result.

I mean you say it can't work as they claim, yet it does and the measured thrust from many devices, calculated in different ways, measured in different ways, in different labs, in different countries all closely matched what their theory says the thrust should be.

With respect, just maybe your explanation / understanding of what is happening inside the frustum is not at the same level as Shawyer or the Chinese?

« Last Edit: 05/19/2015 06:38 PM by TheTraveller »

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"As for me, I am tormented with an everlasting itch for things remote. I love to sail forbidden seas.”Herman Melville, Moby Dick

The number of photons (N) inside a cavity is not conserved. A photon may collide with an electron on a wall, exciting it to a higher energy state, removing a photon. This electron may drop back to its lower level in a series of steps, each one of which releases an individual photon back into the cavity. Although the sum of the energies of the emitted photons are the same as the absorbed photon, the number of emitted photons will vary.

The absorption (emission) of one photon might be accompanied by the emission (absorption) of more than one photon, as long as the frequency of the photons involved are such that the energy of the system remains constant.

N over volume, and the entropy density are proportional to the cube of the temperature of the photon gas, while the pressure and the energy density are proportional to the fourth power of its temperature.

For black body radiation it can be shown that, as a result of this lack of constraint on the number of photons in the system, the chemical potential of the photons must be zero.

One point to keep in mind is that the change from 2GHz to ambient thermal radiation is an up-conversion, that is, it represents a negative entropy change component that must be more than made up somewhere else.

Quote

As an example we consider the Casimir effect with different temperatures between the plates (T) resp. outside of them (T′). For T′ < T the pressure of heat radiation can eventually compensate the Casimir force and the total pressure can vanish...If both T and T′ are fixed (isothermal case), this equilibrium has turned out unstable.